Windowpane Flounder

Windowpane flounder are found in the northwest Atlantic from the Gulf of St. Lawrence to Florida in relatively shallow water. We manage two stocks of windowpane flounder in U.S. waters: Gulf of Maine/Georges Bank windowpane flounder, and Southern New England/Mid-Atlantic windowpane flounder.

Status

• According to the 2017 operational assessment the Gulf of Maine/Georges bank stock of windowpane flounder is overfished and no overfishing is occurring.
• According to the 2017 operational assessment, the Southern New England/Mid-Atlantic stock of windowpane flounder is not overfished and overfishing is not occurring.

Appearance

• Windowpane flounder is a left-eyed species of flounder.
• Windowpane flounder have a rounded body shape—they are nearly as wide as they are long.
• Windowpane flounder have thin, nearly translucent bodies.
• The tips of the first 10–12 rays on a windowpane flounder’s dorsal fin are free (not connected by fin membrane), and as a result, they have a fringe-like appearance.
• The top side (eyed side) of a windowpane flounder is light greenish-brown and covered in small dark brown and white spots, while the bottom side is white.

Biology

• Adult windowpane flounder typically grow to 10–12 inches in length.
• On Georges Bank, some windowpane flounder spawn as early as July or August, but spawning activity peaks in October and November.
• In Southern New England, windowpane flounder typically spawn during the spring and the fall.
• In the Mid-Atlantic, windowpane flounder typically spawn during April to May, with peak spawning occurring in October to November.
• When windowpane flounder are first hatched, their eyes are symmetrical, with an eye on each side of their head. As the fish grows, it flattens out and the right eye moves over to the left side of its head.
• After metamorphosis, young windowpane flounder typically settle to the bottom in inshore areas and migrate to deeper offshore waters as they get older.
• Young windowpane flounder usually feed on copepods that are suspended in the water column, while adult windowpane flounder typically prey on bottom-dwelling organisms such as shrimp, small fish, lobsters, and crabs.

Where They Live

• Windowpane flounder are found in the northwest Atlantic from the Gulf of St. Lawrence to Florida in relatively shallow water.

Management

• We manage two stocks of windowpane flounder in U.S. waters: Gulf of Maine/Georges Bank windowpane flounder, and Southern New England/Mid-Atlantic windowpane flounder.
• NOAA Fisheries and the New England Fishery Management Council manage the fishery.
• Windowpane flounder, along with other groundfish in New England waters, is managed under the Northeast Multispecies Fishery Management Plan, which includes:
  • Permitting requirements for commercial vessels.
  • Separate management measures for recreational vessels.
  • Time/Area closures to protect spawning fish and habitat.
  • Minimum fish sizes to prevent harvest of juvenile fish.
  • Annual catch limits, based on best available science.
  • An optional sector (catch share) program can be used for cod and other groundfish species. The sector program allows fishermen to form harvesting cooperatives and work together to decide when, where, and how they harvest fish.